Axially slidable supporting means for grinding wheels



Jan' 21 C. G. EKHOLM AXIALLY SLIDABLB SUPPORTING MEANS FOR GRINDING WHUEDS Filed Oct. 11, 1939 2 shuts-Shut 2 mvenvon Carl Gusiaf Ekholm UNITED l"s ra'rESf lsitionl by means of v bearings IIJ, II. v On both sides of Patented J an. 2 1, 1941 FPATENT OFFICE 2,229,231 AXIAI-.LY sLIDABLE SUPPORTING MEANS Fon GRINDING WHEELS Carl Gustav Ekholm, Lidkoping, Sweden, assignor to Lidkpings Mekaniska Verkstads Aktlebolag, Fabriksgatan, Lidkoping, Sweden, a corporation of Sweden Application octoberil, 1939, serial No. 298,817 In `Germany October 31, 1938 In some grinding operations good results have been achieved by using a grinding whee1,.which during the grinding operation is simultaneously rotated and displaced-along the workpiece parallel with the grinding wheel axis.v In the known grinding machines `of thiskind .the grinding` wheel was firmly mounted on a spindle, which was bothv rotatably and slidably mounted. This arrangement, however, has the disadvantage that the axial displacement requires considerable /power and results in wear on expensive machine `by that a hub supporting the grinding wheel is slidably mounted on a rotatably mounted spindle by means of balls or rollers, preferably balls, said' thev spindle in the di-" rectionof rotation. According to the invention`v hub being connected with the grinding wheel is easilyslidable with very small power consumption.

An embodiment of the Invention is shown in the accompanying drawings. Fig.l1 shows alongitudinal section through the improved support- Fig. 2 shows a vhorizontal view of a. grinding wheel of a centerless grinding machine ing means.

mounted according to theinvention.

The grinding wheel I shown in Fig. 1 is supported by a sleeve 2 between a flange 3 and a nut 4. The sleeve 2 in its turn isl supported by a hub 5 between a flange B .of the hub 5l and a nut 1. 4

The unit consisting ofthe grinding wheel, the sleeve and the hub is slidablymounted 'on the grinding wheel spindle 8 which on both sides of the grinding wheelis mounted in iixed axial p cvdoubvle row' self-'aligning ball the ball beariings there 'are sealing' members I2, I3, I4, I5. The left end of the spindle in Eig. 1 is connected to a motor (not shown) `for rotation of the spindle. i

In order to facilitate the sliding of the hub 5 on the spindle 8 slidable ball bearings lare arranged between these two-parts at both ends o f 'the hub 5. Each such ball bearing consists of a hardened steel bushing I6 and I1 pressed into the hub and a hardened steel'bushing I8 and I9 8 and ball retainers 20 pressed onto the spindle and 2I freely placed between said bushings and lindrical tube having ments ofthe key 26.

' tending' through a bore in vinternally threaded sleeve 32 encloses the shaft 3| and is in thread-engagement with said shaft. .The sleeve v32 is mounted in `an enlargement of `the bore in the housing 30. `:firmly mounted `on the end of Athe sleeve 32 by means of a nut 35.

:other direction the sleeve has a fixed axial relation to the housing in the one or the other direction. This axial displacement is transmitted through the block 29 well as in its peripheral direction. In'the shown embodiment each ball retainer consists of a cybores for the balls. The balls are retained by lips bent out of the material of the tubel Between the inner hardened steel bushings there is placed an intermediate piece 22 of .some softer material.

. In Fig. 1 the hub 5 is shown in its left end position, there being an interspace between the right end surface of the hub 5 and the adjacent surface of the sealing member I4. To prevent intrusion of grinding dust or other foreign materiai through this interspace into the slide ball f Ybearings the sealing members I3, I4 are provided with projecting sealing ribs 23, 24, which coop- 5' erate with corresponding sealing grooves in the end surfaces of the hub 5.

To promote the axial displacement of the grinding wheel a rod 25 is slidably mounted in 'a longitudinal bore in the spindle 8 and connected with the hub 5 by means of a key 26. The vkey 26 extends through slots 21 cut out in the spindle 8 andthe tube 22. The slots have such a length that they permit the necessary move- The rod 25 extends outside 25 the end of the spindle and is connected with a block v29V by means of double-acting thrust ball bearings 28. The block 29 is slidably but not rotatably mounted in a housing 30 arranged on the outside oi. the machine bed 9. The block 29 is formed with an externally threaded shaft 3l exthe housing 30. An

A hand-wheel 34 is By turning the hand-wheel 34 in the one or the i sleeve 32 is turned. Said 4\ 30. i On account of the thread-engagement between the sleeve '32 and' the shaft 3l this turning results in an axial displacement of the shaft 3l and the thrust bearing 28 to the rod 25 and through the key 26 further to the unit consisting of the hub 5, the sleeve 2 and the grinding wheel I.

In the shown embodiment the key 26 also has the functionto transmit the rotation of the spindle 8 to the hub 5 and the grinding wheel I. Also the rod 25 is rotated, but on account of the double acting thrust bearing 28 the movements of the `spring the grinding wheel non-rotating block 29 can be transmitted to rod 25 even when the spindle is rotating.

' Fig. 2 shows the supporting means according to the invention used in a centerless grinding machine having a grinding wheel Il and a regulating wheel 36 and a work support not shown in the drawings. left end position, the right end position being indicated in dot and dash lines. The workpiece to be ground is a torsion spring having a. cylindrical intermediate portion 31 and two iuted end portions 38 and 39; The intermediate portion is connected with the end portions by transitions forming surfaces of rotation 40, 4| with curved generatrices.

the

The grinding operation relates to the cyllnv drical surface of the intermediate portion and to the surfaces 40, 4| of the transitions. The surface-quality of the transitions is of great importance as to the strength of the finished torsion spring, as4 even small fissures in the transitions act as indications for breakage. It is therefore desirable that the transitions should be ground so as to eliminate all fissures that might have occurred during the foregoing operations in an economical manner.

The end portions of the grinding wheel are used for the grinding of the transitions. For this purpose the end portions of the grinding wheel before the grinding operation are shaped' as surfaces of rotation having curved generatrices, the shape of which'corresponds with the desired shape of the torsion spring. During the grinding of the cylindrical surface of the torsion is axially displaced by turning the hand wheel 34. One of the end portions of the grinding wheel comes in contact with one of the transitions of the torsion spring, and the grinding at the transition is continued until `the operator finds the surface satisfactory. For a satisfactory result of the grinding operation it is necessary that the axial displacement of the grinding wheel during the grinding of the transitions takes place uniformly. In the supporting means according to the invention this isvpossible,

because only a relatively small mass is to be displaced and the slide bearings between the slidable unit and the spindle cause only very little friction.

The invention is not restricted to the embodiment shown in the drawings but numerous modlfications of the same are possible. The slide,

bearings may for instance consists of an inner bushing fixed Yon to the spindle and having axially extending outwardly projecting ribs and an outer bushing connected with the grinding wheel and having inwardly projecting ribs, situated between the rst mentioned ribs and rows of balls or rollers placed between the different ribs. Such slide bearings canalso transmit the rotation of the spindle to the grinding wheel. For this purpose as a further alternative the spindle and the bore of the hub-could be made polygonal preferably square in cross section, and a number of balls or rollers be placed between the hub andl the spindle to reduce the friction when sliding the grinding wheel. When the key is relieved The grinding wheel is shown in its from the function of transmitting rotation it can be arranged out of contact with the slldable rod and the hub, whereby all sliding friction in connection with the movement of the key is obviated. The invention is not restricted to centerless grinding machines but can also be used in connection with grinding machines having fixed centres. Furthermore the invention is not restricted to grinding machines but can also be used in lapping or polishing machines.

1. In a supporting means for a grinding wheel the combination with a rotatably mounted spindle formed with a bore, of a grinding wheel hub and antifriction slide bearings between the hub and the'spindle, a rod slidably mounted in the bore in the spindle, and a connecting member such as a key between the rod and the hub.

2. `In a supporting means for a grinding wheel the combination with a rotatably mounted spindle formed with abore, of a grinding wheel hub and antifriction slide bearings between, the hub and the spindle, a rod slidably mounted in the bore in the spindle, a connecting member such as a key between the rod and the hub, a block mounted slidably but not rotatably in a housing, a thrust bearing situated outside the end of the spindle and connecting the rod with a block.

3. In a supporting means for a grinding wheel the combination with a rotatably mounted spindle of a grinding wheel hub and antifriction slide bearings between the hub and the spindle, a rod slidably mounted in a. bore in the spindle, a connecting member such as a key between the rod and the hub, a thrust bearingsituated outside the end of the spindle and connecting the rod with a block mounted slidably but not rotatably in a housing and provided with a. threaded shaft, an operating sleeve rotatably mounted in the housing and having internal threads in threadengagement with the threaded shaft.

4. In a supporting means for a grinding wheel the combination with a rotatably mounted spindle, of a grinding wheel hub, slidable on the spindle, ball retainers at both ends of the hub containing a number of ballsk distributed axially as well as peripherally, two bushings pressed into the hub at vthe ends thereof and two bushings pressed on to the spindle for coaction with the balls, means for rotating the grinding wheel hub with the spindle and means located between the two sets of balls for CARL GUSTAV EKHOLM.

reciprocating the grindingv wheel hub on the spindle. 

